abstract |
The present invention provides a sensitive and specific indirect homogeneous mobility displacement assay that uses size exclusion chromatography to measure biological products such as vedolizumab and ustekinumab in a patient sample. The assays of the present invention are particularly suitable for detecting the presence or level of biological products that target complex or large antigens including cell surface proteins, transmembrane proteins, strongly glycosylated proteins and multimeric proteins, as well as antigens that cannot. be purified, impure antigens, and partially or substantially purified antigens. The present invention also provides soluble and isolated a4β7 integrin heterodimers, and soluble and isolated IL-12p40 monomers that are suitable for use in the indirect assays described herein. |